Dental facing and backing



Feb. 14,1928. 1,659,510

J. A. ASKEW DENTAL FACING AND BACKING Filed March 25, 1926 i Patented Feb. 14, l928.

f UNITED] STAT-ES PA TENT mm Jenn A. asxnw, or munuiocx; ARKANSAS.

nnman Home AND" Jame? Application fled-lurch 25, inner minimum;

This invention relates to new andauseful improvements in teeth, with particular ref erence to interchangeablefacings and backing placed toward the base of inluse the tooth while A further object of the inventionisetheprovision of a dovetailing wedge and groove formed respectively in the backing and facing designed to prevent lateral movement of the facing and at the same time looking it to the facing, said; wedge and groove tapering toward the apical edge of the tooth at the same angle as the bevel at the lower edge of the facing between the facin and backing, so that the facing can readily be slid into position and secured to the backing, without removing the latter from its permanent mounting in the mouth of the patient.

Still another object of the invention is the provision of an extension or tip at the end of the Wedge on the backing said tip intersecting the thinner part of the facing caused by the undercuttin of the facing to form the transverse shou der hereinbefore referred to, reinforcing the facing against breakage along this line of relative weakness.

Other objects will appear as the following description of a preferred embodiment therei of proceeds.

In the drawings Fig. 1 is a cross section through a tooth embodying the principle of the presentinvention.

Fig. 2 is a front elevation of the backin Fig. 3 is a perspective view of the backing.

Fig. 4 is a perspective view of the facing seen from the rear.

figures, the numeral 1 represents the facin which may be of porcelain and is bevele adjacent its cutting edge, asshown at 2, to

Another, object of the invention is the; pro!- vision of transverse interenga inggshoulders on both backing; and facing, efinitelyv allercating the positionof the'latter with respect; to the backing, assuring it againstbeing-die Referring now in detail to the several' permit the backing 3 to extend forwardly,

tbfthfl cutting: edge on the oeclusall face of i the tooth, for the fnomistrainathereby Olivia-tin ytheihazardy of having it brcheninitheinoutgiv Theifhcingr and: backing'ar e: formed wit transverse. interengaging; shoulders 51 and 61 which definitely allocates the facing with; respect to, the backing, the shoulder on the: hacking; overhanging that, upon the; facing,

thereby; constituting positive means to prevent the. accidental displacement of the facing, toward thebasaofl the tooth.

The. backing is, provided with a wedge, 7 F tapered? 111 a direction towardtlie: occlusali face of: the tooth, and the facingris formed:

with a corresponding: oovei 85 forming a seatfnr said wedges '1: ewedgeiand groove are both undercut laterally so that the wedge dovetails into the groove securely locking the facing to the backing. The interengagement of the wedge and groove also ensures the said parts against relative lateral displacement.

It will be noted that the front face of the wedge 7 tapers at the same an 1e as the angle of the bevel 2. This makes it possible to replace the facin while the denture to which the backing 18 attached, is in the mouth of the patient, the replacement being accomplished simply by pushin the new facing upward and toward thehacking so that the wed e 7 slips into its seat in the roove 8, it eing understood that cement as previously been applied to the contacting surfaces of at least one of said parts.

The wedge 7 is formed with an extension or tip 9 projecting from its smaller end and intersecting the plane ofithe shoulder thereby crossing the region of relative thinness established in the facin by undercutting the same to form the shoul er. The ti extends into the socket 10 in the facing wit in which it is suitably embedded, said socket constituting a reinforcement for the facingat said line ofweakness. The wedge and tip are tapered on the forward side toiprevent the metal coming so close to the front surface of the orcelain as to be reflected through it.

ile I have herein described what I believe tobe a preferred and practical embodiment of my invention itis to be understood that VHIIOIIS ChBJI s in the arran ment and proportions o the parts may%e we of having the baekingmceive the: reet stress incident? to 1 mastioatiom thereby relieviiig the facing made as the dictates of usage may require and still be within the terms ofthe appended claims.

Having described my invention what I claim as new and desire to secure by Letters Patent, is 2- 1. In an artificial tooth, a facing having a portion of its inner side cut away transversely of its width at an angle to its inner side to form a transverse shoulder directed toward the base of the tooth, said facing also having a longitudinal wedge-shaped groove formed on its inner side and taper ing toward said shoulder, said groove terminating at its lower end in a socket below said shoulder and a backing having adownwardly inclined portion projecting from its front face and extending transversely ofsaid face to form a shoulder interengaging the shoulder of said facing, said backing also havinga wedge projecting from its front face and seating in said groove, said wedge intersecting the relatively weak part of said facing adjacent said shoulder and having a tip at its free end extending into said socket, said facing being formed with a transverse beveled portion extending forwardly toward the cutting edge of said facing substantially parallel to the face of said tion inclining downwardlyand away from the body of the backing, anintermediate transverse portion inclined in the same direction and at the same angle, turning downwardly in an abrupt downwardly facing shoulder, and a projecting wedge extending substantially in a direction from the base to apex of the tooth having the upper face thereof inclined in the same direction and at the same angle as the other described inclined surfaces, the facing having complementary inclined surfaces.

In testimony whereof I have hereunto set my hand.

JOHN A. AsKEW, 7 

